The rise of cloud computing wherein services and storage are provided over the Internet enables providing shared resources, software, and information to desktop computers, mobile devices and other devices on demand. Server virtualization enables partitioning one physical server computer into multiple virtual servers. Each virtual server appears to be the same as a physical server and is capable of functioning as a full-fledged server. The combination of cloud computing and server virtualization is powerful in supplying on-demand computing utility and is flexible in efficiently allocating computing resources.
A cloud-computing ready data center requires computing, storage, and communication resources to be efficiently allocated and expanded at a large scale. The data center has to be operating without interruption or with certain guaranteed availability. The availability requirement of applications hosted in a data center may change over time. For example, the geographic replication of server virtualization provides duplicate hardware and software replication in two or more geographic areas which ensures a high rate of availability in a wide variety of situations that disrupt normal business operations. The availability requirement may be relaxed for any one particular data center that houses servers which provide geographic replication of server virtualization within the two or more geographic areas. The data center may need to adapt to the cloud computing and server virtualization environment in a scalable, configurable and efficient manner.
The Uptime data center tier standards, developed by the Uptime Institute, are a standardized methodology used to determine availability in a data center. The tiered system provides a measure for return on investment (ROI) and performance of a data center. The standards comprise a four-tiered scale, with Tier 4 being the most robust, and Tier 1 being the least robust.
In a Tier 1 data center, a single and non-redundant distribution path is used to serve the computing servers, the storage servers and other equipment in a data center. There are no non-redundant capacity components. The cost of a Tier 1 data center may be $3.5 million to $10 million per MW. The guaranteed availability of a Tier 1 data center is 99.671%.
In a Tier 2 data center, in addition to all Tier 1 data center requirements, there are redundant site infrastructure capacity components guaranteeing 99.741% availability. The cost of a Tier 2 data center may be $4 million to $12 million per MW.
In a Tier 3 data center, in addition to all Tier 2 data center requirements, there are multiple independent distribution paths serving the computing servers, the storage servers and other equipment in a data center. All of the servers and other equipment are dual-powered and there are redundant capacity components. The cost of a Tier 3 data center may be $5 million to $15 million per MW. The guaranteed availability of a Tier 3 data center is 99.982%.
In a Tier 4 data center which is considered the most robust and less prone to failures, in addition to all Tier 3 requirements, all components are fully fault-tolerant including redundant capacity components, storage, chillers, Heating, Ventilation, Air Conditioning (HVAC) systems, servers, etc. Everything is dual-powered. The cost of a Tier 4 data center may be over $22 million per MW. The guaranteed availability of a Tier 4 data center is 99.995%.
Tier 4 data centers are designed to host mission critical servers and computer systems, with fully redundant subsystems (cooling, power, network links, storage, etc.) and compartmentalized security zones controlled by biometric access control methods. On the other hand, Tier 1 data centers are least robust but least expensive and may be suitable for less critical applications.
Typical end-to-end data center development projects can take anywhere for twelve months to three years to complete. Data center capacity plans, which normally drive construction, get less reliable and are more susceptible to change. Shorter build cycles of a data center saves costs. Longer build cycles, however, may cause unavailability of longer capacity plan. It may also be necessary to build more idle capacity to accommodate time to build. Stranded and idle data center capacity creates a less optimal Power Usage Effectiveness (PUE) curve and is the equivalent of having an idle factory. The PUE metric compares a facility's total power usage to the amount of power used by the IT equipment, revealing how much is lost in distribution and conversion. An average PUE of 2.0 indicates that the IT equipment uses about 50 percent of the power to the building.
Typical Pre-Construction activities of building a data center include site selection due diligence, governmental negotiations, land purchase, utility service infrastructure, data center design, and obtaining permits. The activities typically take from six to twenty-four months to complete. However, often times, the progress of the Pre-Construction activities may be unpredictable and the schedule may slip. The duration of the Pre-Construction activities normally takes just as long, if not longer than the construction time of a data center. The cost of the Pre-Construction activities, however, is typically a small percentage of the total project cost.
Uninterruptible Power Supply (UPS) is typically used to protect servers and other electrical equipment in a data center where an unexpected power disruption could cause injuries, fatalities, serious business disruption or data loss. UPS units range in size from units designed to protect a single computer to large units powering entire data centers, buildings, or even cities. Battery technology has been improving and is enabling more compact, more efficient, longer lifecycle, and service free batteries that may be used in UPS systems. With the advancement of battery technology, it may be possible to have smaller UPS units that install when the servers install and only operate when servers on server racks are operating. The smaller UPS units save power and upfront cost. The smaller UPS units may be integrated into racks in 0 U space. The smaller UPS units may also have higher voltage input (480 VAC) to avoid 1% to 3% loss during transformation to 208 VAC. Compared with the standard configuration wherein an UPS system is coupled with a Power Distribution Unit (PDU) which supplies power to server racks, a 25% savings in power efficiency may be achieved. Smaller UPS units with advanced battery technology may be service free within the 3 to 4 year lifecycle. There will be no service costs and it is easy to swap upon failure. The cost may be less than one half of the installed cost of standard UPS solutions for a data center.
Servers are typically placed in racks in a data center. There are a variety of physical configurations for racks. A typical rack configuration includes mounting rails to which multiple units of equipment, such as server blades, are mounted and stacked vertically within the rack. One of the most widely used 19-inch rack is a standardized system for mounting equipment such as 1 U or 2 U servers. One rack unit (1 U) space on this type of rack typically is 1.75 inches high and 19 inches wide. A rack-mounted unit that can be installed in one rack unit is commonly designated as a 1 U server. In data centers, a standard rack is usually densely populated with servers, storage devices, switches, and/or telecommunications equipment. While the performance of servers is improving, the power consumption of servers is also rising despite efforts in low power design of integrated circuits. For example, one of the most widely used server processors, AMD's Opteron processor, runs at up to 95 watts. Intel's Xeon server processor runs at between 110 and 165 watts. Processors are only part of a server, however; other parts in a server such as storage devices consume additional power.
Rack-mounted units may comprise servers, storage devices, and communication devices. Most rack-mounted units have relatively wide ranges of tolerable operating temperature and humidity requirements. For example, the system operating temperature range of the Hewlett-Packard (HP) ProLiant DL365 G5 Quad-Core Opteron processor server models is between 50° F. and 95° F.; the system operating humidity range for the same models is between 10% and 90% relative humidity. The system operating temperature range of the NetApp FAS6000 series filers is between 50° F. and 105° F.; the system operating humidity range for the same models is between 20% and 80% relative humidity.
The power consumption of a rack densely stacked with servers powered by Opteron or Xeon processors may be between 7,000 and 15,000 watts. As a result, server racks can produce very concentrated heat loads. The heat dissipated by the servers in the racks is exhausted to the data center room. The heat collectively generated by densely populated racks can have an adverse effect on the performance and availability of the equipment installed in the racks, since they rely on the surrounding air for cooling.
A typical data center consumes 10 to 40 megawatts of power. The majority of energy consumption is divided between the operation of servers and HVAC systems. HVAC systems have been estimated to account for between 25 to 40 percent of power use in data centers. For a data center that consumes 40 megawatts of power, the HAVC systems may consume 10 to 16 megawatts of power. Significant cost savings can be achieved by utilizing efficient cooling systems and methods that reduce energy use.
The cost of building an efficient data center normally is high. A data center that is able to provide flexible availability tier configurations and is able to adapt to the cloud computing and server virtualization environment in a scalable, configurable and efficient manner may provide significant energy and other cost savings.